1. Field of the Invention
The invention pertains to the field of magnetographic printing in which a magnetic field pattern is produced in the form of characters or other indicia to be printed upon a paper or other printing surface.
2. Description of the Prior Art
Magnetic printing has in the past been shown to be technically feasible but heretobefore economically uncompetitive with printers operating upon electrostatic principles. One major difficulty has been that magnetographic printing required complex recording heads and associated drive circuitry. Recording heads used in previous devices required many styli or laminations for each character in a row of characters being printed. Approximately ten styli or laminations were required for each character. For standards of 80 or 132 characters per line, the cost of driving each styli or lamination was economically prohibitive.
A second problem with conventional magnetic printing devices involved the transfer of an image from a recording medium to paper or other printing surface. In such systems, a latent magnetic image of the characters or indicia to be printed was first inscribed upon a magnetic recording surface then rendered visible by the application of magnetic toner particles. The toner particles were then transferred to paper upon which they were fixed by heat. The image to be printed was not immediately visible after recording. It was also difficult to achieve sufficiently dark prints because the transfer of toner from the recording surface to the paper was far from complete. Moreover, the recording surface had to be completely cleaned of all remaining toner particles before it could be re-recorded and used again for another image. Even if small traces of toner were left after each image printing, the traces would eventually build up, seriously effecting the performance of the device.